I would go for SAS. Multilane connections give good speed, reasonably inexpensive, and Fibre Channel seems to be on the outs (getting replaced by iSCSI over Nx10GigE).

I don't think there is much you can do with just 2TB of spinning disk (in any configuration) that will challenge the bandwidth of either. First concern for either IOPS or throughput would be the size and RPM of the disks.